A trip system for a steam turbine closes a trip-and-throttle valve and a control valve of a steam turbine in an emergency. The trip system includes: an emergency shut-off device that shuts off supply of control oil for the trip-and-throttle valve and the control valve to close the trip-and-throttle valve and the control valve; and a drain device that includes a plurality of solenoid valves connected in parallel and drains the control oil by opening the solenoid valves. The emergency shut-off device includes a cylinder, a piston that slides in the cylinder, a spring that applies biasing force to the piston, a plurality of piston valves provided to the piston, and a plurality of chambers formed by the piston valves.